Optical deflectors using liquid crystal are configured such that incident light is output after the deflection direction of incident light is changed by forming predetermined electric field distribution in a liquid crystal layer provided between a pair of substrates. Here, the optical deflector using liquid crystal includes, for example, a first substrate on which a plurality of transparent electrodes are provided in a striped pattern, a second substrate disposed to face the first substrate and provided with a transparent common electrode, and a homogeneous alignment type liquid crystal layer provided between the first substrate and the second substrate, wherein the common electrode is grounded, and a predetermined voltage is applied to each transparent electrode, so that a spatial refractive index modulation region is induced in the liquid crystal layer, thereby forming a blazed diffraction grating in the liquid crystal layer.
Incidentally, in such an optical deflector having the above-described configuration, a short circuit may be formed, for example, between the transparent electrodes adjacent to each other due to a residue, or the like, resulting from etching in forming the transparent electrodes. When the short circuit is formed, the optical deflector generates unnecessary diffracted light at an angle different from a desired diffraction angle during operation. This may make control of the diffraction angle difficult or may reduce the diffraction efficiency.
For example, Patent Document 1 describes a horizontal electric field type liquid crystal device including an array substrate provided with a common electrode and a conductive auxiliary layer which are formed by forming an interlayer insulating layer etched to form a reverse taper shape between electrodes, and separately forming an indium tin oxide (ITO) film in a self-aligning manner on the interlayer insulating layer.